Wollaston published fifty-six papers on ‘pathology, physiology, chemistry, optics, mineralogy, crystallography, astronomy, electricity, mechanics, and botany,’ and almost every paper marks a distinct advance in the particular science concerned. The majority were read before the Royal Society, and published in the ‘Philosophical Transactions.’ The influence of Wollaston's medical training is seen in his first paper on ‘calculi’ (read 22 June 1797), in which he showed that in addition to calculi consisting of uric acid, previously discovered by Scheele, calculi of the bladder might consist of calcium phosphate, magnesium ammonium phosphate, and calcium oxalate (or mixtures of these), to which in 1810 he added ‘cystic oxide,’ now called cystin, thus practically exhausting the subject and rendering rational treatment possible. He also investigated the composition of prostatic and of gouty calculi. In his Croonian lecture in 1809 he showed in a strikingly simple and ingenious way, by means of the ‘muscular murmur,’ that each muscular effort, apparently simple, consists of contractions repeated at intervals of one twentieth or thirtieth of a second. In February 1824, having noticed that at times he saw only half of every object with both eyes, he put forward his important theory of the ‘semi-decussation of the optic nerves,’ now generally accepted. In May 1824 he gave an ingenious explanation of the apparent direction of eyes in a portrait, illustrated by his friend Sir Thomas Lawrence [q. v.]
The investigation of platinum led Wollaston to discover palladium in the platinum ores. Being unwilling to disclose the subject of his work, in April 1803 he sent specimens of the metal (with an anonymous statement of its properties) for sale at the shop of a Mrs. Forster, 26 Gerrard Street, Soho. Richard Chenevix (1774–1830) [q. v.] bought up the stock, worked at it for a month, and read a paper before the Royal Society showing that palladium was not, ‘as was shamefully announced,’ ‘a new simple metal,’ but an alloy of platinum with mercury. Wollaston tried to dissuade Chenevix from his views, but it was not until he had discovered a second platinum metal, rhodium (in 1804), and obtained pure platinum, thus entirely completing his investigation, that he fully acknowledged that the discovery was his in a letter to ‘Nicholson's Journal’ dated 23 Feb. 1805. Wollaston's accuracy was beyond a doubt; and the effect of his conduct, says Thomas Thomson, ‘was to destroy the chemical reputation of Chenevix,’ who thereupon abandoned the science (see Phil. Trans. 1803 pp. 290, 298, 1804 p. 419, 1805 p. 104; Nicholson's Journal, 1803 v. 137, 1804 vii. 75, 159, 1805 x. 204; Annales de Chémie, 1808, lxvi. 83).
Dalton's atomic theory had been first clearly enunciated in 1807 in Thomson's ‘System of Chemistry’ (3rd ed. iii. 425) [see Thomson, Thomas, 1773–1852]. Wollaston accepted it at once, and tried with Thomson's help to convert Sir Humphry Davy [q. v.], but in vain. On 14 Jan. 1808 Thomson read before the Royal Society his well-known paper on the two kinds of oxalates, which was followed on 28 Jan. by Wollaston's more comprehensive memoir on ‘Super-acid and Sub-acid Salts,’ the two papers affording most powerful support to Dalton's views. Wollaston, who had discovered the striking instances of the law of multiple proportions quoted in his memoir some time previously, characteristically withheld them till he should ascertain the cause ‘of so regular a relation;’ but he now put forward the idea that it would be necessary later to acquire ‘a geometrical conception’ in three dimensions of the relative arrangement of the atoms, a suggestion that since 1870 has been realised in the great developments of stereo-chemistry. Wollaston's most important paper in theoretical chemistry is that ‘On a Synoptic Scale of Equivalents,’ published in 1814. In this he proposes, in order to avoid undue use of hypothesis, to replace Dalton's ‘atomic weights’ by ‘equivalents’ which were to express the bare facts of quantitative analysis. Wollaston's criticism of Dalton in this paper is fundamental; but his use of the word ‘equivalent’ was unfortunate, and led to confusion, for which he has been severely criticised (Ladenburg, Entwickelungsgesch. der Chemie, pp. 69–71). The battle between ‘atomic weights’ and ‘equivalents’ lasted, with many fluctuations, down to recent times. For the practical calculations of analysis Wollaston invented a slide rule, which was much used for a considerable time.
In 1814 Wollaston and Smithson Tennant [q. v.], while investigating the subject of gas explosions for the Royal Society, discovered that explosions will not pass through a small tube, a fact utilised independently by Davy in his safety lamp in 1815 (Phil. Trans. 1816, p. 8).
The discovery of a method for producing pure platinum and welding it into vessels, made about 1804 and published as the Bakerian lecture in 1828, has proved of the highest importance, scientific and commercial, from the fact that the metal is attacked by extremely few chemical reagents. The
